Determination of the charged pion-nucleon coupling constant from pp → nn differential cross-section

A recent experiment at LEAR, the CERN Low Energy Antiproton Ring, has provided very precise differential cross-section data for the pp → nn charge-exchange reaction. Extrapolating the data to the pion pole we have determined the charged-pion coupling constant to be fc2 = 0.071 ± 0.002 from the data at 601 MeV/c. Details of the fitting procedure are given, as well as results obtained when applying the same method to recent np → pn data.